Fig. 35.—Gravid segment of pork-measle tapeworm (Tænia solium), showing the lateral branches of the uterus enlarged. (Stiles, Report U.S.A. Bureau of Agriculture, 1901.)
If he discovers cysts, the diagnosis is confirmed, but failure to do so by no means disposes of the possibility of infection. Railliet declares that about one animal in four or five shows no cysts beneath the tongue, and, moreover, fraud is possible in this connection, it being quite possible to prick the little cysts with a needle so that the liquid contents escape, and examination gives no positive result. For these reasons intra-vitam examination alone is now discounted, and the chief reliance is placed on post-mortem search.
Prognosis. The prognosis is very grave, not on account of danger to the lives of the infected, but because infected meat may be offered for human consumption. Should such meat, in an insufficiently cooked condition, be eaten by man, its ingestion is followed by the development of Tænia solium. If cooking were always perfect it would destroy the cysticerci, but the uncertainty in this respect should prevent such meat being consumed. The cysticerci are killed at a temperature of 125° to 130° Fahr.
Fig. 36.—Eggs of pork-measle tapeworm (Tænia solium): a, with primitive vitelline membrane; b, without primitive vitelline membrane, but with striated embryophore. × 450. (After Leuckart.)
Lesions. The lesions are represented by cysts alone—i.e., by semi-transparent bladders, each of which contains a scolex or head armed with four suckers and a double crown of hooks. The little bladders are most commonly found in the muscles, lodged in the interfascicular tissue, which they slightly irritate.
Fig. 37.—Half of hog, showing the portions most likely to become infested with pork measles. (After Ostertag.)
The number present varies extremely, depending on the intensity of infestation and the number of eggs swallowed. Whilst in some cases difficult to discover, in others they are so numerous that the tissues appear strewn with them.
They are commonest in the muscles of the tongue, neck, and shoulders, in the intercostal and psoas muscles, and in those of the quarter.